Class 10 Science · Chapter 3

Metals and Non-metals

225 Class 10 Science questions on Metals and Non-metals from the NCERT textbook, NCERT Exemplar and CBSE board papers 2024–2026, each with its answer and a step-by-step solution.

CBSE Class 10 Science previous year papers, with answers →

Questions · page 4 of 12

1. Q61 Exemplar · Multiple Choice Questions
   The electronic configurations of three elements ​X, ​Y ​and Z are X $-$ 2, ​8; Y $-$ 2, 8, 7 and ​Z $-$ 2, ​8, 2. Which of the following is correct?

   1. (a)X is a metal
   2. (b)Y is a metal
   3. (c)Z is a non-metal
   4. (d)Y is a non-metal and Z is a metal
   Show answer

   (d) Y is a non-metal and Z is a metal

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2. Q62 Exemplar · Multiple Choice Questions
   Although ​metals form basic ​oxides, which of the ​following ​metals ​form an ​amphoteric ​oxide?

   1. (a)$\text{Na}$
   2. (b)$\text{Ca}$
   3. (c)$\text{Al}$
   4. (d)$\text{Cu}$
   Show answer

   (c) $\text{Al}$

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3. Q63 Exemplar · Multiple Choice Questions
   Generally, non-metals are not ​conductors ​of electricity. Which ​of the ​following ​is a good ​conductor of electricity?

   1. (a)Diamond
   2. (b)Graphite
   3. (c)Sulphur
   4. (d)Fullerene
   Show answer

   (b) Graphite

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4. Q64 Exemplar · Multiple Choice Questions
   Electrical wires ​have ​a coating of an ​insulting material. ​The material, ​generally used is

   1. (a)Sulphur
   2. (b)Graphite
   3. (c)PVC
   4. (d)All can be used
   Show answer

   (c) PVC

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5. Q65 Exemplar · Multiple Choice Questions
   Which of ​the ​following ​non-metals is ​a liquid?

   1. (a)Carbon
   2. (b)Bromine
   3. (c)Phosphorus
   4. (d)Sulphur
   Show answer

   (b) Bromine

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6. Q66 Exemplar · Multiple Choice Questions
   Which ​of ​the ​following ​can undergo ​a ​chemical ​reaction?

   1. (a)${\text{MgSO}}_4+\text{Fe}$
   2. (b)${\text{ZnSO}}_4+\text{Fe}$
   3. (c)${\text{MgSO}}_4+\text{Pb}$
   4. (d)${\text{CuSO}}_4+\text{Fe}$
   Show answer

   (d) ${\text{CuSO}}_4+\text{Fe}$

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7. Q67 Exemplar · Multiple Choice Questions
   Which ​one ​of ​the ​following figures correctly describes the process of ​electrolytic refining?

   1. (a)
   2. (b)
   3. (c)
   4. (d)
   Show answer

   (c)

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8. Q68 Exemplar · Short Answer Questions
   Iqbal treated a lustrous, divalent ​element ​M with sodium hydroxide. He ​observed the formation of bubbles in reaction mixture. He made the ​same observations ​when this element was treated with hydrochloric acid. Suggest ​how can he identify the produced gas. Write chemical ​equations for both the reactions.
   Show answer

   M is zinc and the gas is hydrogen, which burns with a pop sound near a burning splint.

   M is zinc. The gas is hydrogen; it is identified by bringing a burning splint to the mouth of the tube, where it burns with a characteristic pop sound. The two reactions are $\text{Zn}+2\text{NaOH}⟶{\text{Na}}_2{\text{ZnO}}_2+{\text{H}}_2$ and $\text{Zn}+2\text{HCl}⟶{\text{ZnCl}}_2+{\text{H}}_2$.

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9. Q69 Exemplar · Short Answer Questions
   During extraction of metals, ​electolytic refining is used to obtain pure metals.

   1. (a)Which material ​will be used as anode and cathode for refining of silver metal by this process?
   2. (b)Suggest ​a suitable electrolyte also. ​
   3. (c)In this ​electrolytic cell, where do we get ​pure silver ​after passing electric ​current?
   Show answer

   Impure silver anode, pure silver cathode and acidified silver nitrate solution; pure silver collects on the cathode.

   (a) The anode is a thick block of impure silver and the cathode is a thin strip of pure silver. (b) A suitable electrolyte is an aqueous solution of silver nitrate acidified with a little nitric acid. (c) Pure silver is deposited on the cathode; the insoluble impurities settle below the anode as anode mud.

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10. Q70 Exemplar · Short Answer Questions
    Why ​should the metal ​sulphides ​and carbonates be converted to metal ​oxides in the process of ​extraction ​of ​metal from them?
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    Metals are obtained by reduction, which works far more easily on oxides, so sulphides are roasted and carbonates calcined to oxides first.

    Because the metal is finally obtained by reduction, and metal oxides are much easier to reduce than metal sulphides or carbonates. Carbon and carbon monoxide take oxygen away readily but cannot strip sulphur or a carbonate group as easily, so the ore is first brought to the oxide: a sulphide by roasting in excess air, $2\text{ZnS}+3{\text{O}}_2⟶2\text{ZnO}+2{\text{SO}}_2$, and a carbonate by calcination in limited air, ${\text{ZnCO}}_3⟶\text{ZnO}+{\text{CO}}_2$. The oxide is then reduced, $\text{ZnO}+\text{C}⟶\text{Zn}+\text{CO}$.

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11. Q71 Exemplar · Short Answer Questions
    Generally, ​when metals ​are treated with ​mineral acids, hydrogen gas is ​liberated but ​when metals (except ​Mn and Mg), treated with ${\text{HNO}}_3$, ​hydrogen is not ​liberated, why?
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    Nitric acid is a strong oxidising agent: it oxidises the hydrogen to water and is itself reduced to oxides of nitrogen.

    Nitric acid is a strong oxidising agent. Any hydrogen the metal displaces is immediately oxidised to water, while the nitric acid is itself reduced to an oxide of nitrogen such as ${\text{N}}_2\text{O}$, $\text{NO}$ or ${\text{NO}}_2$. The metal therefore dissolves as its nitrate and an oxide of nitrogen is evolved instead of hydrogen. Manganese and magnesium are exceptions because with very dilute nitric acid they are reactive enough to release hydrogen before it can be oxidised.

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12. Q72 Exemplar · Short Answer Questions
    Compound X ​and aluminium are ​used ​to join railway tracks.

    1. (a)​Identify the ​compound X ​
    2. (b)Name the reaction
    3. (c)Write down its reaction.
    Show answer

    X is iron(III) oxide; it reacts with aluminium in the thermite reaction, giving molten iron that welds the rails.

    (a) X is iron(III) oxide, ${\text{Fe}}_2{\text{O}}_3$ (ferric oxide). (b) The reaction is the thermite reaction, a highly exothermic displacement reaction, used as thermite welding. (c) ${\text{Fe}}_2{\text{O}}_3(s)+2\text{Al}(s)⟶2\text{Fe}(l)+{\text{Al}}_2{\text{O}}_3(s)+\text{Heat}$.

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13. Q73 Exemplar · Short Answer Questions
    When a metal X is ​treated with cold ​water, it gives a basic salt Y with ​molecular formula XOH (Molecular mass $=40$) and liberates a gas ​Z which easily ​catches ​fire. Identify ​X, Y and Z and also write the ​reaction involved.
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    X is sodium ($\text{Na}$, atomic mass 23), Y is $\text{NaOH}$ and Z is hydrogen: $2\text{Na}+2{\text{H}}_2\text{O}\to 2\text{NaOH}+{\text{H}}_2$.

    X is sodium ($\text{Na}$), Y is sodium hydroxide ($\text{NaOH}$) and Z is hydrogen (${\text{H}}_2$). The reaction is $2\text{Na}(s)+2{\text{H}}_2\text{O}(l)⟶2\text{NaOH}(aq)+{\text{H}}_2(g)$, and it gives out so much heat that the hydrogen catches fire.

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14. Q74 Exemplar · Short Answer Questions
    A ​non-metal X exists in two different forms Y and Z. Y ​is the ​hardest natural ​substance, ​whereas Z is a good conductor of ​electricity. Identify X, ​Y and Z.
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    X is carbon; its allotropes are diamond (Y) and graphite (Z).

    X is carbon, Y is diamond and Z is graphite. Diamond and graphite are two allotropic forms of carbon: diamond is the hardest natural substance, and graphite is the one non-metal that conducts electricity well.

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15. Q75 Exemplar · Short Answer Questions
    The following ​reaction takes ​place when aluminium powder is heated with ${\text{MnO}}_2$ $$3{\text{MnO}}_2(s)+4\text{Al}(s)⟶3\text{Mn}(l)+2{\text{Al}}_2{\text{O}}_3(l)+\text{Heat}$$

    1. (a)Is ​aluminium ​getting reduced?
    2. (b)​Is ${\text{MnO}}_2$ getting oxidised?
    Show answer

    No: aluminium is oxidised because it gains oxygen, and ${\text{MnO}}_2$ is reduced because it loses oxygen.

    (a) No. Aluminium gains oxygen to become ${\text{Al}}_2{\text{O}}_3$, so it is oxidised, and it acts as the reducing agent. (b) No. Manganese dioxide loses its oxygen to become free manganese, so it is reduced, and it acts as the oxidising agent.

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16. Q76 Exemplar · Short Answer Questions
    What are the ​constituents of ​solder alloy? ​Which property ​of ​solder makes it ​suitable for ​welding electrical wires?
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    Solder is an alloy of lead and tin; its very low melting point suits it to welding electrical wires.

    Solder is an alloy of lead and tin, taken in roughly equal proportions. Its very low melting point is the property that makes it suitable for welding electrical wires: it can be melted with a small soldering iron and run into the joint without heating the wires enough to damage them.

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17. Q77 Exemplar · Short Answer Questions
    A metal A, ​which is ​used in thermite process, ​when heated with ​oxygen gives an oxide B, which is amphoteric in nature. Identify A and B. Write ​down ​the reactions of oxide ​B ​with HCl and NaOH.
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    A is aluminium and B is amphoteric aluminium oxide, which reacts with $\text{HCl}$ as a base and with $\text{NaOH}$ as an acid.

    A is aluminium ($\text{Al}$) and B is aluminium oxide (${\text{Al}}_2{\text{O}}_3$), which is amphoteric. With hydrochloric acid it behaves as a base: ${\text{Al}}_2{\text{O}}_3+6\text{HCl}⟶2{\text{AlCl}}_3+3{\text{H}}_2\text{O}$. With sodium hydroxide it behaves as an acid: ${\text{Al}}_2{\text{O}}_3+2\text{NaOH}⟶2{\text{NaAlO}}_2+{\text{H}}_2\text{O}$.

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18. Q78 Exemplar · Short Answer Questions
    A ​metal that ​exists as a liquid ​at room temperature is obtained by heating its sulphide in ​the ​presence of air. Identify the metal ​and ​its ore and give the reaction involved.
    Show answer

    Mercury, obtained from its ore cinnabar ($\text{HgS}$) by roasting in air and then heating the oxide.

    The metal is mercury ($\text{Hg}$) and its ore is cinnabar, mercury(II) sulphide ($\text{HgS}$). Roasting the ore in air gives mercuric oxide, $2\text{HgS}+3{\text{O}}_2⟶2\text{HgO}+2{\text{SO}}_2$, and further heating decomposes that oxide directly to the metal, $2\text{HgO}⟶2\text{Hg}+{\text{O}}_2$.

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19. Q79 Exemplar · Short Answer Questions
    Give the formulae ​of the ​stable binary ​compounds that would be formed ​by the combination of following ​pairs of elements.

    1. (a)​Mg and ${\text{N}}_2$
    2. (b)Li and ${\text{O}}_2$
    3. (c)Al and ${\text{Cl}}_2$
    4. (d)K ​and ${\text{O}}_2$
    Show answer

    (a) ${\text{Mg}}_3{\text{N}}_2$, (b) ${\text{Li}}_2\text{O}$, (c) ${\text{AlCl}}_3$, (d) ${\text{K}}_2\text{O}$: the valencies are crossed over to get the formulae.

    (a) ${\text{Mg}}_3{\text{N}}_2$, magnesium nitride; (b) ${\text{Li}}_2\text{O}$, lithium oxide; (c) ${\text{AlCl}}_3$, aluminium chloride; (d) ${\text{K}}_2\text{O}$, potassium oxide.

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20. Q80 Exemplar · Short Answer Questions
    What happens when

    1. (a)${\text{ZnCO}}_3$ is ​heated in the absence of ​oxygen?
    2. (b)​a ​mixture of ${\text{Cu}}_2\text{O}$ ​and ${\text{Cu}}_2\text{S}$ is ​heated?
    Show answer

    Zinc carbonate decomposes to zinc oxide and carbon dioxide; copper(I) sulphide reduces copper(I) oxide to copper with sulphur dioxide.

    (a) Zinc carbonate is calcined: it decomposes on heating to zinc oxide and carbon dioxide, ${\text{ZnCO}}_3⟶\text{ZnO}+{\text{CO}}_2$. (b) Self-reduction takes place: copper(I) sulphide reduces copper(I) oxide, so copper metal is set free and sulphur dioxide escapes, $2{\text{Cu}}_2\text{O}+{\text{Cu}}_2\text{S}⟶6\text{Cu}+{\text{SO}}_2$.

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